The present invention relates to a method and apparatus to be used when welding two abutting sections of pipe or tubing, and also to purge blocks for establishing a localized inert atmosphere inside two abutting pipe sections in the region of a desired weld joint.
Modern plants for the processing, refinement, and production of oil, petrochemicals, natural gases and other like materials often take place in a manufacturing facility that employs the use of a network of piping. The piping network is a significant component of the facility. To produce this network, a great many sections of piping or tubing are assembled. This assembly is commonly carried out by welding sections of pipe or tubing to each other, to pipe fittings, and to other components of the network.
Due to the nature of the materials oftentimes being transported through this network of piping, the purity of the welds and the possibility of corrosion sites are concerns that must be addressed. Weld sites are often known to be corrosion sensitive points. Therefore, consistency and efficiency in conducting welds is an extremely important concern in establishing the network of piping referenced above.
A generally well known method of joining two abutting pieces of pipe or tubing in light of these concerns is tungsten inert gas (TIG) welding. In TIG welding to goal is to establish an inert atmosphere inside two abutting pipe or tubing sections in the region of the desired weld, as well as an inert atmosphere on the outside of the pipe sections in the region of the desired weld joint.
The general practice in this form of welding has been to fill both pipes or tubing sections, which can be very long, with a protective gas such as argon. Typically, a continuous flow of argon gas is provided throughout the welding operation in order to establish the inert atmosphere near the region of the desired weld. A result of this practice is the consumption of large amounts of argon gas, which in turn causes high costs. Further, this general practice does not address the need and concern for centering the two adjoining pipe sections and keeping them stationary through the welding process. Pipe ends must be centered and aligned in order to effect a good weld and seal. Normally, separate mechanical devices have been used to align and center the pipes.
A known alternative to the above-referenced technique involved the use of purge blocks, dams or plugs, which establish a localized inert atmosphere at the interior surface of a desired weld joint. The basic premise to this particular technique has been to plug both ends of the pipes or tubes to be joined. Embodiments of the plugs have included both separate and interconnected inflatable plugs or seals. Notwithstanding, the use of these prior art plugs have failed to account for the alignment of two abutting sections of pipe or tubing, including the centering of pipe ends and keeping them stationary.
The present invention departs from prior art techniques by presenting a new pipe joining method and apparatus that employs an inflatable bladder that both creates a purge block and further positions and centers two abutting sections of pipe or tubing for use in conventional TIG welding.